Accent lighting is mainly decorative, intended to highlight pictures, plants, or other elements of interior design or landscaping.
For example, reading poor-quality reproductions may require task lighting levels up to 1500 lux (150 footcandles), and some inspection tasks or surgical procedures require even higher levels.
Task lighting is mainly functional and is usually the most concentrated, for purposes such as reading or inspection of materials.
Lighting is classified by intended use as general, accent, or task lighting, depending largely on the distribution of the light produced by the fixture. For critical inspection or color matching tasks, or for retail displays of food and clothing, the color temperature of the lamps will be selected for the best overall lighting effect.Ī demonstration of the effects of different kinds of lighting Lower color temperature lamps have relatively more energy in the yellow and red part of the visible spectrum, while high color temperatures correspond to lamps with more of a blue-white appearance. An incandescent bulb has a color temperature around 2800 to 3000 kelvins daylight is around 6400 kelvins. The color temperature of a white light source is the temperature in kelvins of a theoretical black body emitter that most closely matches the spectral characteristics of the lamp. Shading the light will normally decrease efficacy but increase the directionality and the visual comfort probability.Ĭolor temperature for white light sources also affects their use for certain applications. The more transparent the lighting fixtures are, the higher efficacy. A fixture using replaceable light sources can also have its efficiency quoted as the percentage of light passed from the "bulb" to the surroundings. Nearly any material can be used, so long as it can tolerate the excess heat and is in keeping with safety codes.Īn important property of light fixtures is the luminous efficacy or wall-plug efficiency, meaning the amount of usable light emanating from the fixture per used energy, usually measured in lumen per watt. Some are very plain and functional, while some are pieces of art in themselves. The most important functions are as a holder for the light source, to provide directed light and to avoid visual glare. Lighting fixtures come in a wide variety of styles for various functions. The final death knell for whale oil was in 1859, when crude oil was discovered and the petroleum industry arose. By 1860, there were 33 kerosene plants in the United States, and Americans spent more on gas and kerosene than on whale oil. In the 1850s, the price of whale oil dramatically increased (more than doubling from 1848 to 1856) due to shortages of available whales, hastening whale oil's decline. The use of whale oil declined after Abraham Gesner, a Canadian geologist, first refined kerosene in the 1840s, allowing brighter light to be produced at substantially lower cost. Chandeliers were an early form of " light fixture".Ī major reduction in the cost of lighting occurred with the discovery of whale oil. Candles and glass and pottery lamps were also invented. Fireflies have been used as lighting sources. Oily animals (birds and fish) were also used as lamps after being threaded with a wick. Hundreds of these lamps (hollow worked stones) have been found in the Lascaux caves in modern-day France, dating to about 15,000 years ago. Lamps typically used animal or vegetable fats as fuel. These lamps were made from naturally occurring materials such as rocks, shells, horns and stones, were filled with grease, and had a fiber wick. Prehistoric people used primitive oil lamps to illuminate surroundings. As early as 400,000 years ago, fire was kindled in the caves of Peking Man. With the discovery of fire, the earliest form of artificial lighting used to illuminate an area were campfires or torches.
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